Ancient Underground Quarries of Agiades – Mytilinioi, Samos

⛏️ Inside the underground stone workshops of ancient Samos

In the Agiades area near Mytilinioi, Samos, lies one of the island’s lesser-known yet remarkably interesting archaeological landscapes: the Ancient Underground Quarries of Agiades.

This is not a single quarry, but an extensive system of underground galleries created through the systematic extraction of limestone. Archaeological and geological research has recorded around 45 underground galleries, developed along the slopes of the area at two different levels.

Large quantities of building stone were extracted here and used in some of the most important construction projects of ancient Samos. The quarries therefore reveal a different side of the island’s history: not the finished monument admired by visitors, but the place where the process of building those monuments began.

📍 Location & geological setting

The quarries are located in the Agiades / Koutsodonti area near Mytilinioi, above the plain of Chora and within the wider inland landscape of southeastern Samos.

The underground galleries were developed at an elevation of approximately 150 metres and are arranged in two rows, with a difference in height of around 10 metres between them. Their entrances are mainly oriented toward the south or southeast.

The rock exploited by the ancient quarry workers is a hard yellowish to brown limestone belonging to the so-called Pythagoreio Formation.

The ancient craftsmen appear to have possessed a detailed understanding of the local geology, selecting the most suitable layers for the production of building stone.

🏛️ The large three-part underground quarry

The most impressive of the known quarries at Agiades is a large underground excavation extending approximately 50 metres into the rock, with an average height of around 5 metres and a total width of about 20 metres.

Its interior was divided into three parallel passages.

During quarrying, sections of the natural rock were initially left between the passages as supporting walls. As more material was gradually removed, these walls were reduced to massive pillars that supported the roof.

Some of these rock pillars measure approximately 3 × 8 metres.

The result is an extraordinary underground environment of large artificial chambers, parallel passages and massive stone supports that reveal the scale of ancient quarrying activity.

🪨 How the stone was extracted

Traces of the extraction process can still be seen on the walls and floors of the quarries.

In several places, cut channels and grooves remain visible around the areas from which stone blocks were removed. Characteristic tool marks made by different types of picks and metal implements have also been identified on the quarry walls.

These traces are particularly important to archaeologists and geologists because they provide evidence about ancient extraction techniques and help distinguish between different periods of quarrying activity.

The quarries therefore preserve something similar to a vast record of the work carried out by the people who cut stone from the hillside before it was transported and used in the major building projects of Samos.

🏺 The Archaic phase – 6th century BC

The large three-part underground quarry is considered the most likely candidate for activity already during the 6th century BC.

This dating is supported, among other evidence, by Archaic-period pottery discovered in the quarry area.

The period coincides with the great architectural and economic prosperity of ancient Samos, when large-scale projects were being undertaken at the Heraion, throughout the ancient city and within its water-supply system.

The enormous demand for worked stone meant that organised quarries such as those at Agiades formed an essential part of the technical infrastructure behind the great monuments of ancient Samos.

🏛️ Connection with the Heraion of Samos

One of the most important conclusions of the research concerns the relationship between the Agiades quarries and the Heraion of Samos.

Studies associated with the German Archaeological Institute, based on the composition of the limestone and the scale of the quarrying activity, have linked limestone from Agiades with the construction of the great Temple of Rhoikos at the Heraion.

Research estimates that approximately 6,000 cubic metres of limestone were required for the building activity under consideration at the sanctuary.

This connection makes the quarries particularly significant. The underground galleries visible today formed part of the production chain that supplied material for one of the most ambitious architectural projects of Archaic Greece.

🛤️ The Sacred Way and the Roman period

Quarrying activity at Agiades does not appear to have been limited to the Archaic period.

Limestone from the area has also been identified in the large paving slabs used on the Sacred Way of the Heraion during Roman times.

This renovation dates to the late 2nd and early 3rd century AD, suggesting that quarrying in the area either continued for a very long period or was resumed during later phases.

Researchers estimate that approximately 10,000 cubic metres of limestone were required for the paving of the Sacred Way.

Together with the volumes associated with construction at the Heraion, these major uses represent around 16,000 cubic metres of extracted stone, illustrating the enormous scale of quarrying activity in the area.

⚒️ Different periods, different techniques

The galleries of Agiades are not all identical.

Research has identified differences in their layout, tool marks and extraction techniques. The large three-part underground quarry is probably connected with Archaic activity, while some of the smaller single-chamber galleries of the lower row show characteristics that may be associated with later, possibly Roman, quarrying.

The site can therefore be viewed as a kind of underground archive showing the evolution of quarrying techniques through time.

Even more remarkably, some of the smaller galleries continued to be used into the 20th century for the extraction of small, lightweight limestone slabs.

🔎 Traces of the people who worked here

Unlike a temple or a statue, the quarries mainly tell the story of the people who usually remain in the background of great ancient monuments: the quarry workers and craftsmen.

Tool marks on the walls, cut channels around removed blocks and the layout of the underground spaces themselves are direct traces of their daily labour.

Research into the site has also examined inscriptions and markings in relation to the Eupalinos Tunnel and other monuments of Samos, attempting to understand not only quarrying techniques but also the social environment of the people involved in the island’s major construction programmes.

🔱 Was there a connection with the Sanctuary of Hera?

A particularly interesting, but still unproven, possibility concerns whether the quarries were in some way controlled by the Sanctuary of Hera.

Researchers have noted the repeated appearance of the letters ΗΡ on stone slabs associated with the Eupalinos project and have considered the possibility that the marking may refer to Hera or her sanctuary.

Combined with the documented use of Agiades limestone in the Temple of Rhoikos, this has led to the hypothesis that the Heraion may have exercised some degree of control or supervision over the quarries.

However, this remains a scholarly hypothesis rather than a proven historical fact.

🥾 Access & visiting the area

The quarries lie within a rural and semi-mountainous landscape and are not a conventional organised archaeological site like the Eupalinos Tunnel.

Walking routes in the area connect the ancient quarries with remains of the ancient and Roman water-supply systems and with the northern area of the Eupalinos Tunnel.

The terrain requires suitable footwear and caution. The underground galleries are ancient quarry workings, not a developed show cave, and entering deeply into them should not be treated as an ordinary tourist activity.

👀 What visitors can see

The most impressive feature of the quarries is the sense of scale created by their underground spaces.

Large entrances, artificial chambers, massive rock pillars left to support the roof and clearly visible tool marks allow visitors to understand how entire masses of stone were systematically removed from inside the hillside.

This is not a monument that was designed to impress. It is an ancient workplace that, centuries later, has become a striking artificial underground landscape.

And that is precisely why it deserves an important place on the archaeological map of Samos: behind the Temple of Hera, the paved roads and the island’s great engineering works came the stone — and behind the stone were the people who extracted it.